#include <vector>
#include <iostream>

using namespace std;

int solution1(vector<int> queue) {
  //cout << queue.size() << endl;
  if (queue.size() == 30) {
    return 1;
  }

  int result = 0;
  vector<int> copy = queue;
  copy.push_back(1);
  result = solution1(copy);

  copy = queue;
  if (copy.back() == 1) {
    copy.push_back(0);
    result += solution1(copy);
  }

  return result;
}


int solution2() {
  int boys = 1, girls = 0;

  for (int i = 0; i < 30; ++i) {
    int tmp = girls;
    
    girls = boys;
    boys = boys + tmp;
  }

  return boys + girls;
}

int main(int argc, char const *argv[])
{
  /* code */
  vector<int> queue;

  // cout << solution1({1}) + solution1({0}) << endl;

  cout << solution2() << endl;
  return 0;
}
